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What are the 2 methods of dating in Geologic Time?. __________ and _______________ studied features preserved in rocks & present-day geologic processes. Why is Sir Charles Lyell important? Uniformitarianism . Seven principles of relative dating: . . . . . . .
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__________ and _______________ studied features preserved in rocks & present-day geologic processes. Why is Sir Charles Lyell important? Uniformitarianism
Seven principles of relative dating: • . • . • . • . • . • . • . Who formulated these principles? Who expounded upon these principles?
Original horizontality Superposition Lateral continuity Grand Canyon, Ariz.
A B Inclusions In A & C, granite contains inclusions & is younger than the inclusions. • In B, sandstone is younger than the granite b/c it contains inclusions of granite. Wisconsin C
Ontario, Canada Castaic, Ca Cross-cutting relationships
Types of Unconformities What areconformable contacts? Unconformities What is a hiatus?
What is a Disconformity? • How are disconformities recognized?
What is an Angular unconformity? James Hutton = 1st to recognize & understand the significance of an angular unconformity Siccar Point, Scotland
What is correlation? Why do geologists use correlation? Factors: What are Key beds?
Why are fossils important? What are Index fossils?
Absolute-Dating • ___________________________discovered radioactivity in 1903. • Radiometric dating • Radioactivity • Isotopes
Radioactive decay Alpha decay Beta decay Electron capture
Geologic Time Scale www.acs.appstate.edu/~hagemans/timescale.html How was the Geologic Time Scale Developed?
Can sedimentary rocks be dated radiometrically? Explain. How are they dated?